Causes

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Although the exact reason Bell's palsy occurs isn't clear, it's often linked to exposure to a viral infection. Viruses that have been linked to Bell's palsy include the virus that causes:

Cold sores and genital herpes (herpes simplex)

Chickenpox and shingles (herpes zoster)

Mononucleosis (Epstein-Barr)

Cytomegalovirus infections

Respiratory illnesses (adenovirus)

German measles (rubella)

Mumps (mumps virus)

Flu (influenza B)

Hand-foot-and-mouth disease (coxsackievirus)

With Bell's palsy, the nerve that controls your facial muscles, which passes through a narrow corridor of bone on its way to your face, becomes inflamed and swollen — usually related to a viral infection. Besides facial muscles, the nerve affects tears, saliva, taste and a small bone in the middle of your ear.

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